WASHINGTON — As the United States and its allies began launching airstrikes against the Islamic State in Iraq and Syria in August, another — less public — air war was also heating up: in Afghanistan.

According to the latest Pentagon statistics, US combat aircraft dropped more bombs on Taliban and other militant targets in August than it had in any single month in two years — and nearly triple the monthly average since January.

Officials said they were still compiling the bombing statistics for September but the recent uptick in air attacks in Afghanistan comes as the United States is preparing to pull out about half of its 24,000 troops by the end of the year and curtail most combat operations.

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The stepped-up campaign was viewed by some analysts as an effort to beat back recent Taliban gains ahead of the US drawdown. Others saw it as a preview of what might lie ahead as the Afghan government struggles to maintain its own security and needs sustained US help from the air.

The air power statistics, provided by the US Central Command in response to a Globe request, show 436 “weapon releases” in August, compared with the monthly average of about 150 for the previous seven months. That marks the most in a single month since August 2012, the figures show.

A Pentagon official, asked about the increase in bombing, predicted that the current level would diminish.

“The drawdown of coalition forces in Afghanistan, combined with the increasing combat capability of Afghan security forces, obviously will reduce the level of coalition air activity there in the coming months,” Air Force Lieutenant Colonel Edward Sholtis, a spokesman for US Air Forces Central Command in Qatar, said via e-mail. “But for now there’s no significant, sustained dip in the level of air operations in Afghanistan.”

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Sholtis did not offer a specific explanation for the stepped-up bombing, but military specialists outlined a variety of possibilities. The ramping up could mark an effort to preempt possible attacks on US forces as they steadily withdraw from bases in more remote parts of the country, according to Anthony Cordesman, a military specialist and Pentagon adviser at the Center for Strategic and International Studies.

“We are pulling combat forces out of bases,” he said. “We are shutting down combat outposts. That would have been a key month because the tactics were designed to get us out.”

The attacks also coincide with the height of the so-called fighting season — the warmer months when the Taliban and terrorist groups have historically gone on the offensive.

American military casualties have dropped considerably as Afghan forces have taken on a more primary security role in the country — 48 this year compared with 127 last year, according to official statistics — but US officials in recent days have reported an increase in Afghan military casualties.

US Army General John Campbell, the commander of international forces in the country, last week described to reporters at the Pentagon what he called the “Taliban trying to make a statement as they close out the fighting season.”

He contended that any Taliban gains would be temporary.

“There’s nowhere that we have Afghan security forces that the Taliban can get the terrain and hold the terrain,” Campbell said. “The Taliban may take over a district center or something, but only temporarily.”

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The United States plans to keep some 12,500 troops in the country after January to help support and train the Afghan security forces.

Partly as a result, Campbell said, the number of US aircraft inside Afghanistan available to conduct strikes, gather intelligence, and provide logistical support to the Afghans “will be greatly diminished from what we have today” by the end of the year. Nevertheless, because nearly half of the airstrikes are being conducted by combat aircraft coming from bases or ships elsewhere in the region, the air operations could remain at a high level.

Indeed, some specialists said the recent reliance on more airstrikes foreshadows the next phase of the war in Afghanistan. “Even though we will have less soldiers and Marines on the ground, I think you are going to see the same tempo of operations, air power-wise,” said retired Lieutenant General Richard Y. Newton, the former vice chief of staff of the Air Force. “I believe that we are going to have ‘1-800-air power’ for the conceivable future in Afghanistan.”

Retired Major General Walter D. Givhan, who led the effort to rebuild the nascent Afghan Air Force in 2008 and 2009, agreed. “US air power has been a critical part of the support of the Afghan security force,” said Givhan, now senior vice chancellor at Troy University. “We have made a lot of progress building up their air capabilities but they are still nowhere near approaching what we have and we can give them. That difference that air power can make for the Afghan security forces as they are engaging becomes even more important.”

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A number of analysts, however, also warned that more US airstrikes would probably mean more civilian casualties, a highly contentious issue over the years between the United States and its Afghan allies.

Unlike in Iraq and Syria, however, the US Central Command said it does not plan to release daily statistics on air attacks in Afghanistan.

A Central Command spokesman, Lieutenant Colonel Christopher Belcher, said that in Afghanistan the air operations are responding to the constantly changing needs of US and coalition ground troops who are confronting insurgents. The conflict, he said, “doesn’t lend itself to the type of air operations you are currently seeing conducted in Iraq and Syria against preplanned ground targets.”